Question

An octapeptide ($N{H}_2$-Asn-Glu-Tyr-Lys-Trp-Met-Glu-Gly) is subjected to complete protease and chemical digestion. Based on the results obtained, choose the incorrect option from.

• A. Trypsin generates mixture of dimer and trimer.
• B. Trypsin generates tetramers only.
• C. Cyanogen bromide generates a hexamer and a dimer.
• D. Chymotrypsin generates mixture of dimer and trimers.

Answer 1

Answer: (A)

Trypsin generates mixture of dimer and trimer.

There are various chemicals which are used to digest the protein at different amino acids. These chemicals are called as proteases. Trypsin cleaves lysine and arginine at the carboxyl terminus. Hence, for the given octapeptide, it will generate tetramers only. Cyanogen bromide (CNBr) enzyme cleaves at methionine (Met) residues at carboxyl terminus. Hence, for the given octapeptide, it will generate hexamer and dimer. Chymotrypsin cleaves at the carboxyl terminus of phenylalanine (Phe), tyrosine (Tyr), tryptophan (Trp) and leucine (Leu). Hence, for the given octapeptide, it will generate two trimers and one dimer.

Thus, the correct answer is option A.